1. Field of the Invention
The subject of this invention is a photovoltaic bituminous tile for a photovoltaic roof, the production method of the photovoltaic bituminous tile and the photovoltaic roof laying method.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98
Bituminous tiles are known. We refer substantially to stratified products suitable in particular to roof covering, that is in all cases where there is a flat support structure, whose external surface, e.g. the roof, needs a water-proofing and insulating coating. For example, Tegola Canadese® www.tegolacanadese.com is one of the main makers of these products, placing itself among the best international companies producing and commercializing bituminous tiles. In principle, the production process of a conventional bituminous tile requires one glass film layer unrolled by an accumulator to be sent through a coating station. The coating station has the purpose of associating a bitumen layer both on the upper and lower side of the glass film layer. With the aim of increasing resistance to fire and bad weather, stabilizing minerals are then joined and later some grit) for example made up with shattered stone, pigmented and treated if needed with a ceramic process), which is applied only on the upper surface of the coating and then pressed. The function of the grit is to confer color to the bituminous tile flat surface and at the same time to protect the coating from ultraviolet rays. Finally, a silicon-based removing layer is applied on the lower surface to prevent the batch from attaching to the plant and the tiles from sticking to one of the others during packing.
The multi-layer product, made as such, is then cut into tiles. Finally one can observe that some variations to the conventional bituminous tiles can provide the application to the substrate obtained in such a way with an additional coating layer, that in such cases can be a valuable metal, e.g. copper.
In principle, the use of photovoltaic cells for the production of electrical power is known. On the www.uni-solar.com website for instance, a particular solar cell is described, stratified, obtained with vacuumed rolling process, using amorphous silicon. Such means, in the household field, are usually placed on the roof of the residence or other types of building, and have the purpose of transforming the captured solar energy into continuous electric current which is sent to an inverter and later transformed in alternate for conventional use. Introduced for many years in a multitude of technologies, both as source of energy often subordinate to that traditionally generated and as primary source even if intended exclusively for some particular uses, photovoltaic cells are part of a more complex system in continuous evolution. Every cell, along with others of the same kind, thus creates a photovoltaic system, that is composed of an ensemble of mechanical, electronic and electric components, that participate in capturing and transforming the available solar energy, and converting it in electric energy for the user. This system has been known for more than one hundred years in the field of scientific applications, but has only in recent years been more common also in other sectors. Among these, a niche market includes equipment for buildings in general, such as residences in which solar panels have always been appreciated to a greater extent by the public due to the multiple advantages that, usually, they are able to offer.
The general concept relative to the combination of the photovoltaic cell with a generic product for roof coating, e.g. the tile obtained from inert materials or synthetic tiles is known.
For instance, in patent literature U.S. Pat. No. 5,990,414 (Posnansky) where a photovoltaic roof is described. Over an already existing cover structure, obtained in fibro cement tiles, for each tile, one corresponding photovoltaic cell is joined, then connected in series with one of the other cells, as many as there are tiles, allowing for the realization of a sun-capturing surface. In this case, the solar cells are simply laid on and anchored to an existing tile, by means of adhesive or pins.
In WO00/75455 (Kaneka), a tile is described which, on the one side and on the whole surface, is provided with a recess inside of which there are connector means. The solar cell, in this way can be introduced and vice-versa inside the mentioned recess, allowing the coupling with said connector means.
CH682831 (Von Burg, et al.) again concerns a flat tile, in clay or other natural material, shaped so as to provide the two interlocking superimposable and opposite side edges in such a way as to allow for the continuity of the cover along the plane of the pitch. At least one solar cell is mounted along the upper side, so as to be controlled in the position individually.
Also in the field of synthetic tiles or with synthetic substrate, there are solutions similar to the previous, where the general concept of joining some photovoltaic cells to a tile is substantially known. For example, W02007079584 (Metten et al.) describes a modular system that contains a composite tile, with or without integrating photovoltaic cells, a track system for joining the tiles to the structure, and a wiring system for photovoltaic tiles. An extrusion or moulding process can be used to produce the tiles and the track, including the integration of cells. The tracks are included in the structure. The track and the tile have connecting characteristics so that the track can be interlocked with the tile. Adjacent tiles are applied by means of overlapping. The photovoltaic cells can be moulded inside or associated to the tile. A connecting bar or connecting cables are joined to the track. When the photovoltaic tile is blocked with the track, photovoltaic cell connectors engage the connecting bar or the cables to provide for an electric connection.
US2007193618 (Bressler et al.) describes an integrated solar cover system for converting the solar energy into electrical energy. The system includes a first row of photovoltaic cover tiles, with a number of interconnected photovoltaic cells. The pre-existing products can form part of tiles, e.g. synthetic tiles including the bituminous tiles. The tiles have generally a rectangular form and can have one or more holes for securing them to the structure of the roof. Each tile has a first wing that extends from the base of the tile with at least one hole and provides a first electric conducting material on the first side. The cover tiles include a second localised wing on the second side of the base of the tile and a second hole that goes through said wing and the base of the tile. The second wing furthermore has a second conducting material on the second side of the base of the tile. The first wing is at least partially superimposed on the second wing of the adjacent tile, aligning the holes so as to obtain an electric connection in series.
JP2007051478 (Wakebe) describes a roof with a functional panel able to reduce costs improving waterproofing. The tile that integrates the solar cell is placed next to the adjacent tile by means of interposing a side connecting section. A cover profile is superimposed to the side connecting profile.
All this considered, the following characteristics can be reasonably known:                solar cells and in particular amorphous silicon solar cells;        bituminous tiles;        solutions of conventional tiles that integrate solar cells;        solutions of bituminous tiles combined with solar cells;        roof covers providing photovoltaic cells that transform solar energy in electrical energy used partly for domestic use and partly for heating up water for household use;        roof covers, with bituminous tiles that integrate solar cells, joined by means of overlapping; and        a production system of photovoltaic tiles obtained with extrusion or moulding process used to produce tiles, including the integration of cells.        
In principle the solutions until today adopted seem suitable for use. However, some drawbacks can be ascribed to them, e.g. insufficient capturing capacity of the individual photovoltaic tiles reflecting on the total efficiency of the integrated system in the roof. The existing photovoltaic tiles, moreover, for the most part cannot be walked upon and have a considerable weight above all in relation to the fact that they require heavy metallic carpentry works, e.g. in the realization of the support frame. Other drawbacks can be attributed to the present production method that appears complicated and not easily reproducible on industrial scales at reasonable costs. The same is in relation to the laying of the photovoltaic tiles, as the adopted systems are complex, with overly long laying times and furthermore the roof once laid does not allow for functional and fast maintenance. All this considered, the necessity for enterprises of the sector to find innovative solutions which are able to optimize the solutions to-date used is reasonable.